Former National Security Agency contractor Edward Snowden, who faces espionage charges for disclosing secret U.S. government anti-terrorism programs, has requested asylum in Ecuador, according to the country's foreign minister.

"The Government of Ecuador has received an asylum request from Edward J. #Snowden," Ecuadoran Foreign Minister Ricardo Patiño Aroca tweeted today hours after a plane believed to be carrying Snowden landed in Moscow from Hong Kong, where Snowden had been hiding.

The Aeroflot plane believed to be carrying Snowden arrived at Sheremetyevo Airport at around 5:10 p.m. local time. There were cars with Ecuadoran flags at the airport, but an Ecuadoran diplomat there refused to answer questions.

Ecuador has allowed WikiLeaks' founder Julian Assange to spend a year in its embassy in London to avoid extradition to Sweden, where he faces questioning about sex crime allegations.

The anti-secrecy group released a satatement today that Snowden "bound for a democratic nation via a safe route for the purposes of asylum, and is being escorted by diplomats and legal advisors from WikiLeaks."

According to a report from the Interfax news agency, an unidentified Russian official said Snowden has no Russian visa, so he will remain in the transit area and won't come out of customs. The official was also quoted saying that because Snowden won't pass through border control, Russian authorities can't and won't stop him.

The U.S. State Department said today it had contacted several countries in the Western Hemisphere through which "Snowden might transit or that could serve as his final destinations," a State Department official said.

"The U.S. is advising these governments that Snowden is wanted on felony charges, and as such should not be allowed to proceed in any further international travel, other than is necessary to return him to the United States," the official said.

Hong Kong officials said early today that Snowden left the country "on his own accord for a third country through a lawful and normal channel."

"As the HKSAR Government has yet to have sufficient information to process the request for provisional warrant of arrest, there is no legal basis to restrict Mr. Snowden from leaving Hong Kong," Hong Kong government officials said in a statement.

Snowden's U.S. passport was revoked on Saturday, and Hong Kong authorities were then notified -- but the U.S. notification may have occurred after Snowden already had departed the city, which is a Special Administrative Region of the People's Republic of China.

The Obama administration was left "scrambling" for answers for how the fugitive former NSA contractor was able to jet to Moscow, while Washington slept, despite carrying a passport that can no longer be used, an official said.

"I think it's safe to say we were not aware he left Hong Kong," a senior U.S. official familiar with unfolding events told ABC News. "We have little idea of how he left How Kong."

A State Department Operations Center alert said Snowden's U.S passport was revoked Saturday after the Justice Department finally unsealed charges on Friday that had been filed in the U.S. District Court for the Eastern District of Virginia on June 14, ABC News has learned.

"Consul General-Hong Kong confirmed Hong Kong authorities were notified that Mr. Snowden's passport was revoked June 22," the State Department's senior watch officer informed top officials in a new message.

But whether the U.S. embassy was able to tell Hong Kong in time before Snowden fled, or whether the Chinese officials simply were eager to wash their hands of him and let him go, remains unclear.

A State Department spokesperson said they did not have a comment at this time.

The Russian government has been notified by the embassy in Moscow that Snowden no longer has a valid U.S. passport and that the U.S. "desires to have him deported," according to another message from the Operations Center in Washington.

If Snowden never entered Russian passport control because he was driven from the plane to a foreign embassy, "that means the Russians were looking the other way," the senior U.S. official told ABC News.

Earlier today, WikiLeaks had issued a statement that Snowden left Hong Kong and was "bound for a democratic nation via a safe route for the purposes of asylum, and is being escorted by diplomats and legal advisors from WikiLeaks."

"The WikiLeaks legal team and I are interested in preserving Mr Snowden's rights and protecting him as a person. What is being done to Mr Snowden and to Mr Julian Assange -- for making or facilitating disclosures in the public interest -- is an assault against the people," former Spanish Judge Baltasar Garzon, legal director of Wikileaks and Assange's lawyer said in a statement.

U.S. Dept. of Justice officials said the U.S had contacted authorities in Hong Kong to seek Snowden's extradition, based on the criminal complaint.

"We have been informed by the Hong Kong authorities Mr. Snowden has departed Hong Kong for a third country. We will continue to discuss this matter with Hong Kong and pursue relevant law enforcement cooperation with other countries where Mr. Snowden may be attempting to travel," Department of Justice spokeswoman Nanda Chitre said in a statement.

"What Snowden has revealed has caused irreversible and significant damage to our country and to our allies," Alexander said.

When asked whether there is anything that could prevent another private contractor from accessing and leaking classified information from the NSA's systems, Alexander said, "This is a key issue we've got to work our way through. Clearly, the system did not work as it should have."

"[Snowden] betrayed the trust and confidence we had in him. This was an individual with top secret clearance whose duty it was to administer these networks. He betrayed that confidence and stole some of our secrets," Alexander added. "We are now putting in place actions that would give us the ability to track our system administrators, what they are doing, what they're taking, a two-man rule. We've changed the passwords. But at the end of the day, we have to trust that our people are going to do the right thing."

A one-page criminal complaint filed on June 14 outlined the charges against Snowden. The document was unsealed Friday night.

Snowden has been charged with theft of government property, unauthorized communication of national defense information, and willfully communicating classified intelligence. A government affidavit supporting the charges remained sealed.

As a result of the charges, authorities were seeking to extradite Snowden, who was hiding in Hong Kong since fleeing overseas with a cache of sensitive U.S. documents he obtained while working with the NSA in Hawaii.